As the need for energy continues to grow worldwide, the need for additional energy sources also grows. Non-renewable energy sources remain the major supply of energy throughout the world as renewable energy sources remain too low in quantity to meet much of the demand, and their development has been slow and limited to specific localities. While established non-renewable energy sources (e.g., recoverable coal, conventional oil and natural gas) remain the major energy sources, energy producers must now look to other non-renewable energy sources such as unconventional oil resources (e.g., oil shale, tar-sands, and heavy crude) and unconventional natural gas resources (e.g., gas in pressurized aquifers and coal seams) to meet the increasing demand.
Among these unconventional non-renewable energy sources is sour gas fuel. Sour gas is a source of energy that must be utilized because it has a much longer lifetime as compared with other non-renewable sources. Sour gas is a colorless, flammable, and corrosive natural gas that contains significant levels of hydrogen sulfide (H2S).
Combustion is a commonly used reaction in the field of power generation and one that, in certain instances, can utilize sour gas as fuel. Sour gas, however can be damaging to the mechanical parts of the combustion system at high temperatures and pressures under gas turbine system conditions, and is low in calorific value. Further, when H2S is exposed to air, it easily oxidizes into a sulfur oxide (SOx) such as SO2—an air pollutant. In some instances, direct combustion of sour gas in a gas turbine is not even possible due to the composition and the physical characteristics of the gas, particularly if the sour gas has an H2S content above 5-20%. Thus, sour gas has not previously been considered a particularly useful fossil fuel for combustion processes.
The increasing worldwide demand for energy, however, has forced the use of sour gas as an energy source. There are many global undeveloped and underdeveloped sour gas reservoirs. If these resources are to be used for the generation of power, the ability of a combustion process to handle quantities of H2S is necessary in order to make such application possible. Not surprisingly, much effort is underway worldwide to reduce the economic impact of H2S and sulfur management for sour gas fuels.
Conventionally, in order to avoid the corrosive effects and the pollution associated with combustion of sour gas, pretreatment of the sour gas was required to substantially remove the sulfur compounds from the gas stream—a process known as “sweetening.” For example, an amine gas treating process can be used to “sweeten” the sour gas (i.e., remove the H2S). The major shortcoming of processes for sweetening sour gas is that they are very complex and costly.
Thus, there is a need for a process that utilizes unconventional energy resources to produce energy in an efficient and cost-effective manner. In particular, there is a need for sour gas combustion processes with high efficiency in energy conversion, but without the costly pretreatment of H2S.